The Copernicus Sentinel-2 mission takes us over Alaska’s Columbia Glacier, one of the fastest changing glaciers in the world.

Zoom in to explore this image at its full 10 m resolution or click on the circles to learn more.

The Columbia Glacier, visible just above the middle of the image, is a tidewater glacier that flows down the snow-covered slopes of the Chugach Mountains, which dominate the upper part of the image. The mountains hold Alaska’s largest concentration of glacial ice.

Since the early 1980s, the Columbia Glacier has retreated more than 20 km and lost about half of its total volume. This one glacier accounts for nearly half of the ice lost in the Chugach Mountains.

The changing climate is thought to have caused its retreat. Until 1980, when its rapid and constant retreat began, the glacier’s terminus was observed at the northern edge of Heather Island, which lies near the end of Columbia Bay, the inlet into which the glacier currently flows before draining into Prince William Sound. This satellite image, acquired in September 2023, shows instead the deep mostly ice-free Columbia Bay dotted with numerous icebergs and fragmented sea-ice.

Depending on the amount of sediment coming from the Chugach Mountains, water bodies throughout the image can be seen in an array of colours: clear waters of the Pacific Ocean appear dark blue, while turbid waters in inlets and glacial lakes appear in light blue or cyan.

Columbia is just one of the many glaciers suffering from the effects of climate change. Most of the glaciers around the world are losing mass. However, before the advent of satellites, measuring their retreat and studying their vulnerability to climate change was difficult considering their size, remoteness and rugged terrain they occupy.

Different satellite instruments now can gather information systematically and over large areas, providing an effective means to monitor change, keep track of all calving stages and quantify the melting rate and their contribution to sea-level rise.